Chemical heating blanket



July 19, 1966 L. M. SHERMAN 3,261,347

CHEMICAL HEATING BLANKET Filed May 27, 1965 :Fg .IL.

INVENTOR Lou/3 7 Sherman a 2: awm. ATroRNEYs.

United States Patent 3,261,347 CHEMICAL HEATING BLANKET Louis M.Sherman, 732 Wesley Ave.,

Ocean City, NJ. 08226 Filed May 27, 1965, Ser. No. 459,480 9 Claims.(Cl. 126-263) The invention described herein may be manufactured andused by or for the Government for governmental purposes, without thepayment to me of any royalty thereon.

The invention relates to chemical compositions capable of generatingheat and to a novel blanket or bag which provides controlled heatrelease when activated and which operates automatically subsequent toactivation.

Previous proposals for generating heat by chemical agents prescribedvarious comminuted metals that were reacted with suitable oxidizingagents and in other instances with moisture or air. Difficultiesencountered with mixtures of this type stem from the fact that thereactions were vigorously exothermic resulting in rapid heat releasewhich found utility mainly in therapeutic heating pads or in thepermanent waving of hair.

Exothermic reactions which are set up by introducing water into a drypowder mixture will often generate steam and gases that are disagreeableor even dangerous. Contamination or possibly objectionable chemicalaction was heretofore carefully avoided by confining the dry ingredi-'cuts in a porous bag which in turn was enclosed in a rubberized fabricor other waterproof casing. Structures fabricated in this manner tend tobe somewhat rigid and suitable only for localized heat applications inthe manner of the ordinary hot water bottle or electric heating pad.

The chemical heating blanket of the present invention provides for theuse of a relatively thin, pliable cover or wrapping that can be readilyunfolded and spread over a patient as a first aid measure at the sceneof an accident, in emergency situations and in warfare. A clinicallyprescribed expedient for the comfort and survival of the injured andwounded provides for the immediate application of external heat,although such care is seldom available as a first aid treatment. Also,troops and emergency crews deployed in remote, cold regions andoperating under adverse conditions may find immediate and temporaryrelief from the cold by utilizing emergency blankets capable ofgenerating moderate heat for several hours.

It is therefore a primary object of the present invention to provide anovel blanket or bag which is capable of generating moderate heat bymeans of a chemical reaction.

Another object of the invention is to provide compositions which cansustain a uniform, comfortable heat release for a period of severalhours.

A further object of the invention resides in the use of a novel blanketthat is chemically treated and stored for emergency situations, saidblanket being relatively easy to activate for releasing heat for aprolonged period of unattended operation.

A still further object is to provide novel heating compositions whicheliminate operational hazards of the prior art, said compositions beingsubstantially free of gaseous formation and operable without the needfor water or other activating chemical.

Other objects and advantages will become apparent from the detaileddescription that follows.

In accordance with the invention, a paper, fabric, plastic or otherpliable material is formed into a blanket or bag structure andimpregnated with an exothermic compound or mixture of exothermiccompounds to provide a relatively slow release of heat. The blanket maybe formed of any suitable absorbent material in any desired thicknessthat is sufficient to retain in its structure an exothermically reactivecompound. Compounds which can be utilized for this purpose are theper-aminoethylenes and certain organometallics, namely, thealkylaluminums and alkylzincs. The peraminoethylenes which are effectivefor this purpose are those which are chemiluminescent, i.e., those whichdisplay the property of emitting blue-green light when exposed to air.These peraminoethylenes are also capable of a low release of heat, andthey have been found to be effective when used alone, or when mixed witha diluent as an impregnation in the present blanket structures. Morespecifically, a peraminoethylene by way of example is the liquidcompound,

identified as tetrakis (dimethylamino) ethylene which upon exposure toair reacts with oxygen to produce luminescence and heat. Impregnationsof this compound in terry cloth, or other blanket material, will producetemperatures as high as 140 F., while more moderate temperatures ofabout IOU- F., may be sustained for several hours.

The term organometallics is strictly applied to compounds that containcarbon-metal bonds and more particularly to alkylaluminums andalkylzincs. The compounds, triethylaluminum and triisobutylaluminum, aswell as the diethylzinc and dibutylzinc are unstable liquids and becomespontaneously flammable in air with considerable release of heat.However, these compounds may be mixed with suitable inert materials ordiluents to suppress their pyrophoric nature and yield heat at arelatively low rate which is safe and comfortable for body warmth incovering and wrapping media. When the reactive compound combines withoxygen in the air under controlled conditions the heat of the reactionis distributed throughout the diluent material, and the temperature doesnot rise drastically or get out of control. Diluents which are suitablefor this purpose include the neutral hydrocarbon oils, fluorocarbons andother heatand-fire-resistant materials.

Thus, the instant impregnating compositions consist essentially of afire-resistant material in whichone or more of the alkylaluminum,alkylzinc or of other organometallic compound becomes highly diluted. Awide range of weight ratios is possible for these ingredients dependingon the reactivity of the particular compound used and the extent towhich the heat of the reaction will be permitted to develop. The heat ofthe reaction is controlled by the concentration of the organometalliccompound as well as the surface area in which said compound is exposedto air. Heat generation is considerably more rapid when a large surfaceof reactive composition is exposed at once to the action of the air; asectionally exposed surface on the other hand provides a more gradualheat for a prolonged period of operation. Effective heat release inaccordance with the invention is obtained when the organometallics areincluded in an amount in the range of between 0.25 and 25 percent byweight of the impregnating compositions. Mixtures of TEA and TIBA or ofDEZ and DBZ may be used With the diluents with equally effectiveresults.

The penamin'oethylenes may also be mixed and used with minor amounts [ofdiluent materials when lesser reactivity and greater control of heatgeneration is de' sired.

In order to protect the user or patient from possible ill effects, theimpregnated blanket material is treated to form a protective surfacebarrier of thin film of any suitable resin or plastic material. Thus,paper, woven cloth, cellulose matting, and the like, may be resintreated or coated to provide an impervious surface to the liquidimpregnation. The impregnated material may also be protected from theaction of air or moisture by storing it in a hermetically sealedcontainer until the time when it is placed in operation.

The invention is illustrated and further described in the followingpreferred embodiments:

FIGURE 1 is a fragmentary perspective view of a heating blanketconforming to my invention; and

FIGURE 2 is a cross section view of another embodiment of the invention.

Shown in FIGURE 1 is a blanket structure 11 comprising an absorbentlayer 12 of terry cloth, felt, crinkled paper, etc. which is impregnatedwith a heating composition consisting essentially of dibutylzinc mixedwith a neutral hydrocarbon oil, the organometallic being present thereinin about 0.75 percent by weight. An example of a suitable neutral oilwhich may be used for this purpose is the Esso product marketed asNumber 75 neutral oil. The inner surface 13 is formed of a thin film ofTeflon or Mylar. Mylar is the trade name of a film of polyethyleneterephthalate resin manufactured by E. I. du Pont de Nemours & Co. andis available in film thicknesses of 0.00025 to 0.0075 inch.

In view of the reactivity of the zinc compound, the impregnation andplastic coating are carried out in an inert atmosphere. After theblanket has been completed, it is placed in a container and sealed undernitrogen or other inert gas. When the sealed container is opened, theblanket is removed and immediately placed in service to cover anindividual or as a warm wrapping for his extremities or any object whichis to be kept warm. The exposed surface of the blanket allows air andmoisture to react with the zinc compound generating heat and causing arise in temperature on the blanket surface. A temperature of about 108F. may be readily maintained for a period of at least 8 hours.

In the embodiment shown in FIGURE 2, an impregnated pliable layer of aplastic foam 17 having an open cell structure is impregnated with aperaminoethylene compound, or alternately, with a mixture oftriisobutylaluminum and fluorocarbon oil, the aluminum compound beingpresent in said mixture in about 0.5 percent by weight. A film of Mylar,polyvinyl, chloride, etc. is applied to the surfaces of the foam andincluding ends 19. Alternately, a thin aluminum foil 21 may be used inplace of the plastic to protect the outer surface of said layer. Thelayer may be folded or rolled for storage Without the need forhermetical sealing as in the previous embodiment. In placing the blanketlayer in operation, the outer plastic or foil is peeled back orpunctured to introduce air to the impregnation. As the reactive compoundbecomes exhausted during operation, additional sections of plastic orfoil are removed to expose fresh quantities of compound to the action ofair.

Fluorocarbons which are suitable as diluents for the present blanketimpregnations are, for example, the perfiuoroheptane, CqH B.P. 82 C. andthe perfluoromethylcyclohexane, B.P. 76 C. Methods for making these andother fluorocarbons that may be used in the practice of the presentinvention are described in Industrial & Engineering Chemistry, vol. 39,pp. 236-434 (1947).

It will be seen that the present heating blanket provides a novelheating source which remains reactive for several hours without the needfor wetting with water or other initiating agent. It will further beseen that the present chemically treated blanket may be set in operationmerely by exposing impregnated surfaces to the action of air. Under thecontrolled conditions of this invention, an alkylaluminum or otherorganometallic reacts slowly with oxygen to produce an alkoxide andfurther With moisture to form hydroxides. Thus, the blanket remains dryand free of obnoxious gases or steam during the course of its operation.

Further it would be apparent that by constructing the blanket of resintreated paper or woven fabric it is possible to provide an inexpensiveheating blanket which may be readily disposed after it has served itspurpose.

From the foregoing description it is evident that many modifications andvariations are possible without departing from the spirit and scope ofthe instant invention.

What is claimed as new and is desired to be secured by Letters Patentis:

1. A chemical heating blanket comprising a pliable, absorbent layerimpregnated with a mixture of an exothermic compound selected from thegroup consisting of a peraminoethylene, triethylaluminum,triisobutylaluminum, diethylzinc and dibutylzinc and a diluent selectedfrom the group consisting of neutral oil and fluorocarbon, said layerhaving a surface film impervious to said mixture.

2. A chemical heating blanket comprising a pliable, absorbent layerimpregnated with a peraminoethylene, said layer being resin coated toform a surface barrier impervious to said compound.

3. A chemical heating blanket comprising a paper sheet impregnated witha mixture of an alkylzinc and a diluent oil, said alkylzinc comprisingabout 0.25% to 25% of said mixture by weight, said sheet being coatedwith a film of polytetrafluoroethylene.

4. A chemical heating blanket comprising a pliable sheet of plasticfoam, said sheet being impregnated with a mixture of an alkylaluminumand a diluent oil, said alkylaluminum comprising about 0.25% to 25% ofsaid mixture by weight, said sheet being coated with a resin imperviousto said mixture.

5. A chemical heating blanket in accordance with claim 2 wherein saidlayer is coated with a film of polyethylene terephthalate resin.

7 6. A chemical heating blanket in accordance with claim 2 wherein saidlayer consists of terry cloth.

7. A chemical heating blanket in accordance with claim 3 wherein saidalkylzinc consists of dibutylzinc.

8. A chemical heating blanket in accordance with claim 4 wherein saidalkylaluminum consists of triisobutylaluminum.

9. A chemical heating blanket in accordance with claim 2 wherein saidlayer consists of woven cloth.

References Cited by the Examiner UNITED STATES PATENTS 2,384,720 9/1945Babcock et al. 126-263 2,573,791 11/ 1951 Howells. 2,589,645 3/1952Tiegel 126-263 3,064,640 11/1962 Donath 126-263 CHARLES J. MYHRE,Primary Examiner.

1. A CHEMICAL HEATING BLANKET COMPRISING A PLIABLE, ABSORBENT LAYERIMPREGNATED WITH A MIXTURE OF AN EXOTHERMIC COMPOUND SELECTED FROM THEGROUP CONSISTING OF A PERAMINETHYLENE, TRIETHYLALUMINUM,TRIISOBUTYLALUMINUM, DIETHYLZINC AND DIBUTYLZNIC AND A DILUENT SELECTEDFROM THE GROUP CONSISTING OF NEUTRAL OIL AND FLUOROCARBON SAID LAYERHAVING A SURFACE FILM IMPERVIOUS TO SAID MIXTURE.